NEW YORK (Reuters Health) - Most doctors do not recommend
flu shots to their pregnant patients, who are more likely to
develop serious complications if they do get the flu, according
to a new report.

In the review of past studies, researchers also found that
pregnant women had concerns about the safety of the flu vaccine
and tended to underestimate the risk that the virus posed to
themselves and their fetus.

"The research is clear that healthcare providers are not
providing advice to pregnant women about the importance and
benefits of getting vaccinated," Marie Tarrant told Reuters
Health in an email. She worked on the study at Li Ka Shing
Faculty of Medicine at the University of Hong Kong.

"In addition, they are not making influenza vaccine
available to their pregnant clients," she said. "By their
silence, they are sending a message that influenza vaccine is
actually not that important."

One study found pregnant women were five times as likely to
be hospitalized with the flu as other women, Tarrant said.

Flu vaccines given to pregnant women not only immunize them
but protect their infants against the flu until they are six
months old, the researchers write in the journal Vaccine.

The World Health Organization recently identified pregnant
women as the highest priority group to receive seasonal flu
vaccines. The U.S. Centers for Disease Control and Prevention
recommends the vaccines for women who are pregnant during flu
season.

Tarrant and her co-author Carol Yuet Sheung Yuen analyzed
data from 45 studies to learn more about why pregnant women do
or do not get flu shots.

The studies included women from the U.S., Canada, Australia,
Hong Kong, India, Turkey and various European countries. Most of
them found that fewer than 60 percent of pregnant women received
flu shots, and one showed vaccination rates below two percent.

A recommendation from a healthcare provider was one of the
most consistent predictors of getting a flu shot, the
researchers found. Women whose providers recommended flu shots
were between 20 and 100 times more likely to get vaccinated.

However, several studies found that providers offered
negative advice about flu shots and in some cases, explicitly
discouraged them.

The results were not surprising to Dr. Flor Munoz, a
pediatrics and infectious disease researcher at Baylor College
of Medicine in Houston, who was not involved in the current
study.

"If doctors recommended the vaccine, people would take it,"
she told Reuters Health. "This paper is asking providers to be
more vocal in recommending the vaccine to pregnant women."

The primary reason obstetricians cite for not advising
pregnant women to get the vaccine, Munoz said, is that they do
not stock it in their offices.

"They don't carry it," she said. "They see it as a burden,
and they don't think it's worth it. For them to be able to get
their return on investment is difficult, and that's why they
don't do it."

The new review also found that pregnant women often worried
about vaccine safety and side effects. One study found that 45
percent of pregnant women perceived the vaccine as unsafe and
nearly 80 percent believed it could cause birth defects.

Some pregnant women were particularly concerned that
mercury, present in certain flu vaccines, could harm their
unborn children, the authors write.

Multi-dose vials of the flu vaccine contain small amounts of
thimerosal, a mercury-containing preservative that prevents
bacterial growth. Single-dose vaccine vials do not contain the
preservative and are frequently available for pregnant women,
Tarrant said.

"The amount of thimerosal in influenza vaccines is very
small, and it has been shown repeatedly that it is not harmful,"
she said. "However, pregnant women may be more willing to accept
the vaccine without thimerosal. So often that is provided."